JPH036584B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording/reproducing device equipped with an indexing function for recorded contents, and in particular, by changing the duty ratio of a control signal used to control the recording/reproducing operation of a main signal. The present invention relates to a magnetic recording/reproducing device for use in the present invention.

In a magnetic recording/reproducing device such as a video tape recorder, if an index signal corresponding to the recording section of the main signal such as an audio signal or a video signal recorded on the magnetic tape is recorded on the magnetic tape together with the main signal, the data can be reproduced. At times, the index signal can be used for various automatic operation controls such as finding the beginning of a recording section of a desired main signal and detecting the end of a tape.

In general, magnetic recording and reproducing devices equipped with index signal recording and reproducing functions forcibly write the index signal at the beginning of the main signal recording operation, but it is also possible to specify an arbitrary recording section and write the index signal. If it is possible to delete unnecessary index signals, the index function can be used more effectively.
For example, when searching for a recording section of a target main signal using an index signal, if the unnecessary index signal is not written, not only can the search operation be performed quickly, but also there is a risk of malfunction. This will also decrease.

Furthermore, providing a recording track dedicated to the index signal on the magnetic tape in order to record the index signal not only increases the size of the device, but also limits the recording area due to the tape width. This is undesirable because the recording area becomes smaller.

SUMMARY OF THE INVENTION Therefore, the present invention provides a magnetic recording device having a control track on which a control signal is written corresponding to a recording track of a main recording signal, such as a video tape recorder using a rotating magnetic head device. A magnetic recording device with a new configuration in which index signal information is written according to the duty ratio of the recorded control signal, and the writing and erasing operations of the index signal can be performed corresponding to any recording section. The present invention provides a playback device.

Hereinafter, the present invention will be described in detail with reference to the drawings showing one embodiment.

FIG. 1 shows an example of the configuration of a tape running system in a video tape recorder to which the present invention is applied. The tape 2 is fed out from the supply tape reel 3 and wound onto the take-up tape reel 4.
It is guided by each guide pin 5. A full width erasing head 6 is provided upstream of the rotating magnetic head drum 1, and an audio head 7 and a control head 8 for recording and reproducing audio signals and control signals are provided downstream. The audio head 7 and control head 8 are, as shown in FIG.
It is integrally built into one head case 9.

The magnetic tape 2 running in the tape running system as described above is a video track formed at a predetermined inclination angle Θ with respect to the tape running direction, as the tape format is shown in FIG.
Regarding the TR _V , a video signal is recorded and reproduced by the rotating magnetic head device 1, and an audio track is formed along one side edge of the magnetic tape 2.
Regarding TR _A , an audio signal is recorded and reproduced by the audio head 7, and the magnetic tape 2
Control signals are recorded and reproduced by the control head 8 on the control track _TRC formed along the other side edge.

In FIG. 4, which shows the circuit configuration of the essential parts of an embodiment in which the present invention is applied to a videotape record equipped with the above-mentioned tape running system, the audio head 7 is connected via the first switch circuit 11. The first circuit is selectively connected to the output side of the recording amplifier 21 or the input side of the reproducing amplifier 22. Further, the control head 7 is selectively initially connected to the output side of the recording amplifier 23 or the input side of the reproducing amplifier 24 via the second switch circuit 12. Each of the above-mentioned switch circuits 11 and 12 operates according to the recording mode and reproduction mode supplied via the first signal input terminal 31.
The switching operation is controlled by the REC/PB signal, and in the recording mode, each recording amplifier 21, 2
Audio head 7 and control head 8 are connected to the output sides of 2, respectively, and in playback mode, the audio head 7 and control head 8 are
are connected to the input side of each regenerative amplifier 22, 23.

A recording amplifier 21 connected to the audio head 7 amplifies an audio signal (Audio) supplied via a second signal input terminal 32 and supplies the amplified audio signal to the audio head 7.
The audio signal is recorded on the audio track TR _A.

Furthermore, the reproduction amplifier 22 connected to the audio head 7 amplifies the reproduction audio signal (PB.Audio) reproduced by the audio head 7 in the reproduction mode and outputs it via the muting circuit 25. ing. This muting circuit 25 is configured such that an index write command signal (INDEX.WR) and an index erase command signal (INDEX.ER) supplied to the third and fourth signal input terminals 33 and 34 are input to an OR gate circuit 4.
9 as a mutating control signal (MUT), and the operation is controlled in accordance with the mutating control signal.

Furthermore, the recording amplifier 23 connected to the control head 8 receives a vertical synchronizing signal VD supplied from a fifth signal input terminal 35 via a third switch circuit 13, and receives a vertical synchronizing signal VD from a fourth monostable multivibrator 44, which will be described later. The supplied index write signal (WR.INDEX) or the index erase signal (ER.INDEX) supplied from the sixth monostable multivibrator 46 is amplified and supplied to the control head 8, and the magnetic tape is A control signal CTL having index information is recorded on the second control track _TRC . Note that the third switch circuit 13
is the REC/ from the first signal input terminal 31.
Its operation is controlled by the PB signal, and it is closed during the recording mode to supply the vertical synchronizing signal VD to the recording amplifier 23. Furthermore, a reproducing amplifier 24 connected to the control head 8 amplifies and outputs a reproduction control signal (PB.CTL) reproduced by the control head 8 in the reproduction mode, and outputs the amplified reproduction control signal (PB.CTL) to a servo circuit (not shown) of the table running system. supply Furthermore, the reproduction control signal (PB.CTL) outputted via the reproduction amplifier 24 is
The signal is supplied to the trigger input terminal of the first monostable multivibrator 41 via the fourth switch circuit 14. The first monostable multivibrator 41 supplies an output signal with a pulse width of T ₁ to each trigger input terminal of the second, third and fifth monostable multivibrators 43 and 45. The second monostable multivibrator 42 supplies an output signal with a pulse width of _T2 to the second switch circuit 12 as a control signal, and during the period of the pulse width of _T2 , the output side of the recording amplifier 23 is forcibly connected to the control head 8 via the second switch circuit 12. Further, the third monostable multivibrator 43 supplies an output signal with a pulse width of T ₃ to the trigger input terminal of the fourth monostable multivibrator 44 . Furthermore, a fifth monostable multivibrator 45
supplies an output signal with a pulse width of _T5 to the trigger input terminal of the sixth monostable multivibrator 46. Here, the fourth switch circuit 14 receives an index write command signal (INDEX.WR) or an index erase command signal (INDEX.ER) from the third or fourth signal input terminals 33, 34 as a control signal. It is supplied via an OR gate circuit 47. The fourth monostable multivibrator 44 also receives the index write command signal (INDEX.
The sixth monostable multivibrator 46 is controlled to enable reversal operation by the index erase command signal (INDEX.ER). ing.

In the embodiment configured as described above, the index information writing operation can be performed by the operation shown in the time chart of FIG.

First, in the normal recording mode in which video signals and audio signals are recorded as main signals on the video track TR _V and audio track TR _A of the magnetic tape 2, a control signal based on the vertical synchronization signal VD is generated as in a general video tape recorder. (R _ec CTL) is the control track.
As shown in FIG. _5A , the control track _TRC is 1/1/2 of the vertical synchronization signal.
Magnetization is performed such that the direction is reversed every two periods T ₀ . In other words, in the control track TR _C ,
A control signal CTL with a duty ratio of 50% is recorded.

Then, when the control signal CTL recorded in the control track _TRC is played back, the fifth
As shown in FIG. B, a reproduction control signal (PB.CTL) is obtained in which a rising differential pulse and a falling differential pulse are repeated every cycle _T0 . Normally, the rising differential pulse obtained as the reproduction control signal (PB.CTL) every 2·T ₀ , that is, every vertical cycle period V, is used for servo control of the tape running system.

Therefore, in this embodiment, the index information is provided by changing the duty ratio of the control signal CTL so as to shift the generation timing of the falling differential pulse without impairing the generation timing of the rising differential pulse. That is, in order to enter the playback mode for playing back the main signals (video signals and audio signals) recorded on the magnetic tape 2, and write the index information corresponding to the recording section of the desired main signal, the procedure shown in FIG. 5C is performed. When the index write command signal (INDEX.WR) as shown is supplied to the third signal input terminal 33, the write command signal (INDEX.WR)
The muting circuit 25 and the fourth switch circuit 14 are controlled to be in the on state for a predetermined period _TW specified by the above. Therefore, audio head 7
The playback audio signal (PB.Audio) from is muted. In addition, the control head 8
The playback control signal (PB.CTL) from
is supplied to the trigger input terminal of the monostable multivibrator 41. The first monostable multivibrator 41 is triggered every rising differential pulse of the reproduction control signal (PB.CTL), and outputs an output signal with a pulse width of T ₁ during the period T _W as shown in FIG. 5D. Output. As shown in FIGS. 5E and 5F, the second and third monostable multivibrators 42 and 43 operate on each trailing edge (in this example, the rising edge) of the output signal from the first monostable multivibrator 41. output signals with respective pulse widths of T ₂ and T ₃ are triggered at the timing of the downlink). Furthermore, the fourth monostable multivibrator 44 is triggered at the timing of the trailing edge (falling edge in this example) of the output signal from the third monostable multivibrator 43, as shown in FIG. _5G. Outputs an index write signal with a pulse width of Here, each pulse width T ₁ , T ₂ , T ₃ , T ₄ of each output signal from each monostable multivibrator 41 , 42 , 43 , 44 is set to 1/2 period T ₀ of the vertical synchronization signal. On the other hand, it is set so that T ₁ +T ₃ <T ₀ T ₀ <T ₁ +T ₃ +T ₄ <T ₁ +T ₂ <2·T ₀ . That is, the width of each pulse is set so that the index write signal (WR.INDEX) is output from the fourth monostable multivibrator 44 during a period that includes the falling differential pulse of the reproduction control signal (PB/CTL). T ₁ , T ₂ , T ₃ , and T ₄ are set.
By writing the above index write signal (WR.INDEX) to the control track _TRC of the magnetic tape 2 via the control head 8,
The control track _WRC is in a magnetized state as shown in FIG. 5H, and the duty ratio is, for example,
The control signal CTL of 33% is now recorded. Therefore, the normal control signal CTL
The duty ratio of the control signal is 50%, while the duty ratio of the control signal during the above period T _W is 33%.
% can indicate index information. Note that the playback control signal (PB.CTL) when changing the above duty ratio is
As shown in the figure, the generation timing of the rising differential pulse is shifted only by the generation timing of the falling differential pulse, so that the servo control state of the tape running system is not adversely affected. Furthermore, the above index information can be written in correspondence with any recording section of the main signal using an index write command signal.

Additionally, the index information written as described above is sent to the index erase command signal (INDEX.ER).
By supplying the signal to the fourth signal input terminal 34, the data can be erased by the operation shown in the time chart of FIG.

That is, by changing the duty ratio, a control signal given index information is recorded, and an index erase command signal (INDEX.ER) corresponding to the section of the magnetized control track _TRC as shown in FIG. 6A is generated. When supplied to the fourth signal input terminal 34, the sixth monostable signal is input after a period (T ₁ +T ₅ ) has elapsed from the timing of the rising differential pulse of the reproduction control signal (PB.CTL) as shown in FIG. 6B. multi vibrator 4
6 is triggered and an index erase signal (ER.INDEX) with a pulse width of _T6 is output. FIG. 6D shows the output signal from the first monostable multivibrator 42, and FIG. 6E shows the output signal from the second monostable multivibrator 42. The operations of the first and second monostable multivibrators 41 and 42 are similar to the time chart in FIG. 5 described above. Further, the fifth monostable multivibrator 45 is triggered at the timing of the trailing edge (falling edge in this example) of the output signal from the first monostable multivibrator 41, and as shown in _FIG. Outputs an output signal with a pulse width of Here, the predetermined period specified by the index erase command signal (INDEX.ER) is
T _E is set longer than the predetermined period T _W by the index write command signal, and the pulse width T ₅ of each output signal from the fifth and sixth monostable multivibrators 45 and 46 is
T ₆ is set so that T ₅ <T ₃ T ₁ +T ₅ +T ₆ =T ₀ . That is, the index signal from the sixth monostable multivibrator 46 includes the generation timing of the falling differential pulse of the reproduction control signal (PB.CTL), and also includes the generation timing of the falling differential pulse of the regular control signal. It is set to fall. The above index erase signal (ER.
By writing INDEX) into the control track _TRC , the magnetization state of the control track _TRC becomes the state in which the regular control signal CTL with a duty ratio of 50% is recorded, as shown in FIG. 6H. return. Therefore, it becomes possible to reproduce the reproduction control signal (PB.CTL) as shown in FIG. 6 with the index information erased.

Furthermore, in this embodiment, during the operation periods T _W and T _E for writing and erasing the index information,
Since the muting circuit 25 is activated and the reproduced audio signal (PB.Audio) is muted, the index write signal (WR.
INDEX) and index erase signal (ER.
INDEX) to control head 8, control head 8 and audio head 7
Noise due to crosstalk between the regenerative amplifier 2
It is possible to prevent the output from being output via 2. The control signal 8 normally records a rectangular wave signal in saturation, so when the signal is supplied to the control head 8 during playback of the main signal, the signal is superimposed on the playback audio signal (PB.Audio) via the audio head 7. There is a high possibility that this will happen. If an unnecessary signal is superimposed on the reproduced audio signal (PB.Audio), it will be output as noise. Please note that the above playback audio signal (PB.
To apply muting to the audio), the gain of the regenerative amplifier 22 may be controlled, or the frequency characteristics may be controlled.

As described above, in this embodiment, index information can be written corresponding to any recording section of the main signal, and unnecessary index information can be erased. Moreover, since the index information is given by changing the duty ratio of the control signal, it can be written without providing a recording track dedicated to the index. Furthermore, since the reproduced audio signal is muted during the writing and erasing operations of the index information, no unpleasant noise is output.

As described above, the present invention has the function of recording and reproducing the main signal and the control signal independently,
In a magnetic recording/reproducing device that writes index information by making the duty ratio of the control signal recorded on the control track of a magnetic recording medium different from the normal value, the duty ratio of the control signal recorded on the control track is made different from the normal value. Means is provided to form a recording signal to return to the value of the index by a pulse signal of a predetermined length synchronized with the reproduction control signal and supply it to the control signal recording means, and erase the index information by writing the recording signal to the control track. As a result, control signals can be rewritten accurately and unnecessary index information can be arbitrarily deleted. Moreover, in the magnetic recording and reproducing apparatus according to the present invention, a muting means is provided in the reproduction output system of the main signal, so that the main signal is Since muting is applied, it is possible to prevent unpleasant noise caused by the erasing operation from being output as an audio signal during the erasing operation of unnecessary index information.

Therefore, according to the present invention, it is possible to provide a magnetic recording and reproducing apparatus that can arbitrarily erase unnecessary index information without outputting unpleasant noise as an audio signal.

[Brief explanation of the drawing]

FIG. 1 is a plan view schematically showing a configuration example of a tape running system in a video tape recorder to which the present invention is applied. FIG. 2 is an external perspective view showing the structure of an audio head and a control head disposed in the tape running system. FIG. 3 is a plan view schematically showing the recording format of the magnetic tape run in the tape running system. FIG. 4 is a block diagram showing the circuit configuration of a main part of an embodiment in which the present invention is applied to the video tape recorder. FIG. 5 is a time chart for explaining the index information writing operation in the above embodiment. FIG. 6 is a time chart showing the index information erasing operation in the above embodiment. 1...Rotating magnetic head device, 2...Magnetic tape,
3, 4... Tape reel, 5... Guide pin, 6... Full width erase head, 7... Audio head, 8... Control head, 11, 12, 13, 14... Switch circuit, 21, 23... Recording amplifier, 22, 24
... Regenerative amplifier, 25 ... Muting circuit, 3
1, 32, 33, 34, 35...Signal input terminal, 4
1, 42, 43, 44, 45, 46... Monostable multivibrator, 47, 49... OR gate circuit, TR _V ... Video track, TR _A ... Audio track, TR _C ... Control track.

Claims (1)

[Claims] 1. Recording and controlling the main signal and control signal independently.
In a magnetic recording and reproducing device that has a playback function and writes index information by making the duty ratio of the control signal recorded on the control track of the magnetic recording medium different from the normal value, the control recorded on the control track of the magnetic recording medium is A recording signal for returning the duty ratio of the signal to a normal value is formed by a pulse signal of a predetermined length synchronized with a reproduction control signal, and means is provided for supplying the recording signal to a control signal recording means, and the recording signal is written to a control track. In addition to erasing the index information, a muting means is provided in the reproduction output system of the main signal, so that the main signal is muted during the period in which the duty ratio of the control signal by the recording signal is returned to the normal value. A magnetic recording/reproducing device characterized in that it is configured as follows.